Tokamak D-T neutron source models for different plasma physics confinement modes

Neutronic studies of European demonstration fusion power plant (DEMO) have been so far based on plasma physics low confinement mode (L-mode). Future tokamaks, nevertheless, may likely use alternative confinement modes such as high or advanced confinement modes (H&A-mode). Based on analytical formulae used in plasma physics, H&A-modes D-T neutron sources formulae are proposed in this paper. For that purpose, a tokamak random neutron source generator, TRANSGEN, has been built generating bidimensional (radial and poloidal) neutron source maps to be used as input for neutronics Monte-Carlo codes (TRIPOLI-4 and MCNP5). The impact of such a source on the neutronic behavior of the European DEMO-2007 Helium-cooled lithium–lead reactor concept has been assessed and compared with previous results obtained using a L-mode neutron source. An A-mode neutron source map from TRANSGEN has been used with the code TRIPOLI-4. Assuming the same fusion power, results show that main reactor global neutronic parameters, e.g. tritium breeding ratio and neutron multiplication factor, evolved slightly when compared to present uncertainties margin. However, local parameters, such as the neutron wall loading (NWL), change significantly compared to L-mode shape: from −22% to +11% for NWL.

► HCLL DEMO neutronics is based on plasma physics L-mode, but may use H or A mode.
► Based on Plasma Physics 0D code, H&A-mode D-T neutron sources formulae are proposed.
► TRANSGEN code is built to create 2D source maps as input for Monte-Carlo codes.
► A-mode neutronic impact is compared to L-mode at same power on a HCLL DEMO design.
► Results show TBR and Me slight changes, contrary to NWL profile: from −22% to +11%.